feat(example): improve example perfomance

example/lib/card_view.dart

@@ -9,48 +9,38 @@ class CardView extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return Card(
+    return Container(
-      child: Stack(
+      padding: const EdgeInsets.all(16.0),
-        children: <Widget>[
-          SizedBox.expand(
-            child: Material(
-              borderRadius: BorderRadius.circular(12.0),
-              child: Container(
-                color: Colors.blueAccent,
-              ),
-            ),
-          ),
-          SizedBox.expand(
-            child: Container(
       decoration: const BoxDecoration(
         gradient: LinearGradient(
-                      colors: [Colors.transparent, Colors.black54],
+          begin: Alignment.topCenter,
-                      begin: Alignment.center,
+          end: Alignment.bottomCenter,
-                      end: Alignment.bottomCenter)),
+          stops: [
+            0.5,
+            1,
+          ],
+          colors: [
+            Colors.blueAccent,
+            Color.fromARGB(255, 6, 28, 61),
+          ],
         ),
       ),
-          Align(
-            alignment: Alignment.bottomLeft,
-            child: Container(
-                padding: const EdgeInsets.symmetric(
-                    vertical: 16.0, horizontal: 16.0),
       child: Column(
         mainAxisAlignment: MainAxisAlignment.end,
         crossAxisAlignment: CrossAxisAlignment.start,
         children: <Widget>[
-                    Text(text,
+          Text(
+            text,
             style: const TextStyle(
                 color: Colors.white,
                 fontSize: 20.0,
-                            fontWeight: FontWeight.w700)),
+                fontWeight: FontWeight.w700),
+          ),
           const Padding(padding: EdgeInsets.only(bottom: 8.0)),
           Text("$text details",
               textAlign: TextAlign.start,
               style: const TextStyle(color: Colors.white)),
         ],
-                )),
-          )
-        ],
       ),
     );
   }

example/lib/main.dart

@@ -31,13 +31,10 @@ class MyHomePage extends StatefulWidget {
 
 class _MyHomePageState extends State<MyHomePage> {
   int counter = 4;
+  final cardController = SwipeableCardSectionController();
 
   @override
   Widget build(BuildContext context) {
-    //create a CardController
-    SwipeableCardSectionController cardController =
-        SwipeableCardSectionController();
-
     return Scaffold(
       appBar: AppBar(
         title: Text(widget.title),